Characterization of Polyimides by Combining Mass Spectrometry and Selective Chemical Reaction

Selective chemical reaction was employed to overcome problems related to molecular characterization of polyimides due to their insolubility. N-Methylethanolamine was used to induce ring opening, and chain cleavage was carried out by reaction with hydrazine. These reactions were used to enhance solubility of poly(trimellitic anhydride-co-4,4‘-methylenedianiline), poly(pyromellitic dianhydride-co-4,4‘-oxydianiline), and its amic acid form in MALDI and ESI friendly solvents, thus enabling their qualitative analysis by these techniques for the first time. Derivatives of poly(trimellitic anhydride-co-4,4‘-methylenedianiline), made with 2-fluoro-1-methylpyridinium p-toluenesulfonate to introduce charge on the polymer, were used to increase ionization efficiency and intensity in positive ion MALDI spectra.